Cosmos DB Provider

Non-relational provider with its own parallel query pipeline. Uses JSON for document materialization.

When to Use

• Working on Cosmos SQL generation
• Working on document storage, partition key configuration, or CosmosClientWrapper

Key Differences from Relational

• No migrations — use EnsureCreated()
• Documents as JSON — owned and complex types become embedded objects
• Partition key configuration required for performance
• ETag for optimistic concurrency
• No cross-container joins

Azure Cosmos DB Emulator in Docker

Cosmos tests on Helix start the emulator from the work item via PreCommands that run a Docker container using:

• eng/testing/run-cosmos-container.ps1
• eng/testing/run-cosmos-container.sh

These scripts can be invoked locally for testing on machines that don't have the emulator installed, but have docker available.

The Test__Cosmos__SkipConnectionCheck=true env var is set to prevent tests from being skipped when the emulator failed to start.